#include<iostream>
using namespace std;

int main()
{
	int m, t, s;
	cin >> m >> t >> s;
	if (m * t - s < 0)
	{
		cout << 0 << endl;
	}
	else 
	{
		cout << (m * t - s) / t << endl;	
	}

	return 0;
}
